A Means of Instituting Some Degree of Revenue Control in a Bar

A means of instituting some degree of revenue control in a bar which does not use guest checks is:

A) to collect for each drink when it is served;
B) to collect at the end of each hour for all drinks served during that hour;
C) to permit no one but a regular customer to pay for all the drinks he has consumed in an evening as he leaves the bar.